Question

if a light wave is reflected from the surface of the medium,which property of light wave will change with the reflected wave

Answer 1

The refractive index is a measure that determines the reduction of the speed of light to propagate through a homogeneous medium. More precisely, the refractive index of the phase change per unit length, ie the number of wave in the medium () is often larger than the wave number in vacuum (). Wikipedia refractive index.
think when you shout in the mountains and hear the echo, which is what changes in the reflected wave?